1. Field of the Invention
This invention relates to devices for sensing and indicating the proportion of water in a hot water tank that is heated, assuming the heated water accumulates from the top of the tank downward.
2. Description of Prior Art
With a conventional tank type residential hot water heater, a person has no way of knowing if there is enough hot water in the tank to take a shower or bath. This is especially true when multiple people in a house use hot water for showers, clothes washing, and dish washing.
U.S. Pat. No. 5,956,462 (Langford) discloses a vertical series of temperature sensors on a water heater storage tank to determine the vertical level of stratified heated water in the tank. A single heating element is provided at the bottom of the tank with a flue to guide heated water to the top of the tank to stratify it. The sensors give input to a microprocessor that calculates a “need” index to be compared to an electric utility company priority index that is transmitted to the microprocessor from the electric utility. This determines when power is applied to the heater, based on user need and supplier priority. Thus, it reduces peak concurrent electricity demand from users for a power utility. However, it does not provide a visual display for the user from the temperature sensors.
U.S. Pat. No. 5,067,170 (Nagashima et al.) also discloses a vertical series of temperature sensors on a water heater storage tank to determine the vertical level of stratified heated water in the tank. A small secondary water tank with a heating element and temperature sensor is used to heat water and circulate it to the top of the main tank. The amount of hot water to be maintained in the main tank is selectable, thus potentially saving water and/or energy. A controller stops the heating process when the selected level of stratified heated water in the main tank is reached.
These automated devices are unnecessarily complex, yet they still do not give a user the information and control of the present invention. No automated device can fully predict the times and amounts of hot water used by multiple people in a house, especially on weekends, with people on flexible work schedules, with children, and with visitors. These prior devices are too complex to be retrofitted to an existing conventional hot water heater tank.